Lindsay wrote:
From an efficiency point of view, a steam cycle with double reheat would make much more sense, but the big challenge is the reactivity of sodium with water and steam.

If some salt or lead eutectic were used as the secondary coolant, the risk of sodium-water/steam coolant will be eliminated. That is why I wonder when (not if) it will be done.

When I made that first post that's what I was thinking, keep sodium in the primary loop if it performs better and run Lead-Bismuth Eutectic (LBE) or something chemically non-reactive in the intermediate loop.

I just did a quick search on corrosion resistance to molten lead and 316 SS came up a number of times, this would also be a good material for making steam generators out of from a corrosion/chemical compatibility perspective on the water/steam side. Others may know a lot more about good material choices for LBE, but the secondary coolant doesn't have to be LBE.

Why would you bother using a coolant in a secondary loop that you did not use in the primary because you deemed its technological readiness too low? If you want to understand their choices, you have to stay coherent.

Boris H wrote:Why would you bother using a coolant in a secondary loop that you did not use in the primary because you deemed its technological readiness too low? If you want to understand their choices, you have to stay coherent.

I might be misunderstanding the point that you're trying to make I haven't deemed the technological readiness of LBE or sodium anything.

The suggestion to use LBE as secondary coolant is to side-step the chemical reactivity issue and associated risk with having sodium on one side of a heat exchanger and high pressure water/steam on the other. If sodium coolant is the reason to do some inefficient never done before power train, why not look at an alternative coolant, run a more efficient power conversion system and make more MW?

For those who can read french and are interested by Sodium Fast Reactors, the CEA released nine very interesting documents on the SFR technology ( design, safety, fuel, historical backround, etc... these docs contain some informations about phénix, superphénix and ASTRID ).

Sadly there were a lot of SFRs which have encountered problems (and not only technical problems but administrative and political problems too for example Superphénix). But there were also some which worked well (for example the EBR II, the BN-600 and Phénix).

The conceptors of ASTRID have the experience of all the problems encountered with previous SFRs, so normally ASTRID should work well. The great unknown is the nitrogen turbine which is the biggest innovation (but maybe they will swap it for a conventionnal steam turbine).

But we don't know yet if ASTRID will be built, there are a lot of political opposition.

Thanks for the information. The nitrogen turbine seems like a huge development risk to me. What is the largest nitrogen turbine-generator set ever built ? Not in the ballpark of 600 MWe, I guess. Alstom is the partner for the power conversion unit, but now has been acquired (at least the power business) by General Electric, which means that final decisions regarding development are likely to be made in Connecticut, USA and not in Paris or Belfort anymore.

Sad to see that there is very little information about molten salt reactors on the French pages of the CEA. It is only mentioned once or twice as a fourth generation reactor type. All CEA eggs are apparently in the ASTRID basket, which I also regard as a duplication of effort, because these fourth generation SFR types are also being developed in other countries (the new BN-800 is already operating in Russia).

It also remains to be seen how this ASTRID project will progress after the elections in France next year. This ASTRID project is likely to be dead in the water if Hollande and the Socialists are re-elected to government.

Thanks for the information. The nitrogen turbine seems like a huge development risk to me. What is the largest nitrogen turbine-generator set ever built ? Not in the ballpark of 600 MWe, I guess. Alstom is the partner for the power conversion unit, but now has been acquired (at least the power business) by General Electric, which means that final decisions regarding development are likely to be made in Connecticut, USA and not in Paris or Belfort anymore.

Sad to see that there is very little information about molten salt reactors on the French pages of the CEA. It is only mentioned once or twice as a fourth generation reactor type. All CEA eggs are apparently in the ASTRID basket, which I also regard as a duplication of effort, because these fourth generation SFR types are also being developed in other countries (the new BN-800 is already operating in Russia).

It also remains to be seen how this ASTRID project will progress after the elections in France next year. This ASTRID project is likely to be dead in the water if Hollande and the Socialists are re-elected to government.

Nitrogen turbines are effectively the same as air turbines though right? What's stopping people from simply ordering a lot of frame 7 based rigs and ganging them together? Balance of plant from having multiple turbines would suck, but the turbine costs should go down significantly. At least Rod Adams's felt using conventional aeroderivative turbine designs with the associated data/supply chain was a smarter choice.

Alstom is the partner for the power conversion unit, but now has been acquired (at least the power business) by General Electric, which means that final decisions regarding development are likely to be made in Connecticut, USA and not in Paris or Belfort anymore.

If the CEA finances the development I guess they will surely do it.

This ASTRID project is likely to be dead in the water if Hollande and the Socialists are re-elected to government.

For now it seems very unlikely that Hollande will be re-elected, it will probably be the nominee of "Les Républicains" (the classical right side party). However even if the right side party wins there will be a lot of opposition against ASTRID, there are a lot of problems right now with the funding of the EPRs at Hinkley Point.

Nitrogen turbines are effectively the same as air turbines though right?

As Lindsay said earlier in this thread, this turbine will be quite different from the usual gas turbines. The pressure is much higher than with usual gas turbines and the temperature much lower. Also there is not just the turbine to develop but the entire loop, especially the sodium-nitrogen heat exchangers.

All CEA eggs are apparently in the ASTRID basket, which I also regard as a duplication of effort, because these fourth generation SFR types are also being developed in other countries

They already have a lot of experience with SFRs. Taking the MSR path would be like beginning from scratch. And they don't have a lot of financing and time (they want an industrial generation 4 reactor ready before 2040).

But I would also prefer that they work on MSRs or molten salt cooled reactors.

Nitrogen CCGTs? What about the supercritical CO2 Brayton Cycle?

Hot liquid sodium reacts chemically with steam and CO2 but not with nitrogen so that is why they want to use nitrogen for ASTRID. It is an important element for the safety demonstration.

However the supercritical CO2 cycle seems very good for molten salt reactors.

The plan is to reduce the size of ASTRID from 600 MW electric to between 100 and 200 MW electric. It makes you wonder about its purpose and R&D progress in general, because its very predecessor from the 1970s, the Phenix reactor, located at the same site (Marcoule) was even larger than this planned ASTRID reactor.

*The French government has informed Japan that it plans to freeze a next generation fast-breeder nuclear reactor project, the Nikkei business daily reported on Thursday.

* Japan, which has been cooperating with Paris on the fast-breeder development in France, has invested about 20 billion yen ($176.27 million) in the project, the report added.

* The French government will halt research into the Astrid (Advanced Sodium Technological Reactor for Industrial Demonstration) project in 2019, with no plans to allocate a budget from 2020 onwards, the report said, without citing sources.

* France was initially planning to invest 1 billion euros ($1.14 billion) into the project by 2019, before deciding whether to go ahead with construction by the mid-2020s, the report added.

* The freeze would be another blow to Japan’s nuclear ambitions after the country pulled the plug in 2016 on an $8.5 billion Monju prototype fast-breeder project designed to realise a long-term aim for energy self-sufficiency after decades of development.

* The nation’s nuclear industry is also still reeling from the aftermath of the Fukushima disaster in 2011.

* Japan’s Chief Cabinet Secretary Yoshihide Suga said on Thursday that he had not been informed that France had told Japan about a policy to freeze the project.

“We have been currently continuing discussions on cooperation on a fast-breeder reactor with France, and I have been informed that nothing has been decided,” he said in a regular news conference.

* French state nuclear agency CEA has said it proposed the French government scale down a planned prototype breeder reactor to 100-200 megawatts from 600 megawatts.

* Breeders can burn spent uranium fuel, plutonium and other nuclear waste products. Russia is the only nation to have working breeder reactors.

Russia is the only one with working fast reactor. China and India are also building. It would be sensible for others to sell them their RG plutonium stocks for using up. They could also use thorium plutonium fuel rather than a uranium plutonium MOX.